It’s that time of the year, when winter is holding on ferociously, spring is around the corner, and summer is not far behind.  As managers of lakes and ponds it’s time to reassess our annual algae and vegetation management plans / prescriptions. As a professional we are always asking what, why, when, where, and how did / didn’t our plan work.

We must give credit where it’s due: algae’s basic function alongside the rest of the terrestrial world (tress, plants, etc.), is to produce oxygen for the environment we live in. However, as the temperatures begin rising, algae growth can take on a whole new meaning for lake and pond owners. Algae begins growing unchecked and becomes an ugly, unsightly mess that is ruining the tranquility and beauty of your recreational pond.

Professional lake, pond, or water managers (consultants) are always trying to get one step ahead of algae. For the reasons mentioned above, no person loves seeing that green floating scum on their water. There are many variables contributing to algae growth: fishery type, slope, depth, livestock, water source, and previous use of pond are just a few. The list can go on and on.

As a pond owner, the control of algae starts by assessing the current goals for the pond. There is no “one size fits all” recommendations or products to control algae. Two major reasons are that no two ponds are the same, and as a manager, that wouldn’t be doing justice to the pond or owner by giving you a “one size fits all” approach.

Goals and current events will determine what methods are used to treat algae. If there is an event happening in two days, chemical treatment that result in dead brown mats of algae won’t be received very well by guests.

It’s the job of the consultant to discuss all available options, provide information, and ask and answer questions to ensure the best recommendations for that specific lake or pond. Remember — no two ponds are alike and no product is labeled “one size fits all.”

So, what options are out there?

Nutrient Reduction

Plants need nutrients to grow, algae included. Reducing the amount of nutrients, especially nitrogen and phosphorus, will limit the amount of algae present in your lake or pond. No one will be able to eliminate nutrients completely, especially if you have fishery. Nitrogen and phosphorus are two main nutrients required by algae, phosphorus being number one overall.

Constructed lakes and ponds are heavily influenced by their surrounding environment, such as runoff from degraded land, agriculture, and lawn practices.

Management of nutrient into the pond can be achieved by constructing wetlands, building buffers in-between nutrient source and waters edge, creating a floating island planted with herbs/flowers you love, or creating an aquatic plant buffer that pertains to the goals of the lake or pond.

Nutrient reduction can also be achieved through chemical, biological, and mineral applications. These treatments are applied by spraying, injecting, or dispersing over the treatment site. Nutrient reduction is a key step in managing algae for the long term. It is not a quick fix.

Sunlight Reduction

Limiting the amount of sunlight is effective in managing filamentous algae, but not for eliminating other species. Pond dyes produce different shades of color that inhibit the sunlight that is available for plants or algae to use.

If you are daring enough, utilizing another plant species that inhibits the light from penetrating the bottom of the lake or pond can be effective and risky. You must chose the right species for the environment and temperature in your geological region.


The number one species for controlling algae is tilapia, but they can be restricted by state Fish and Game Agencies. In certain states tilapia is restricted to growing in a controlled environment (aquaponics systems), and in other areas only species that die when temperature falls below 60 degrees Fahrenheit. Tilapia should be stocked in minimum densities of 15 pounds per acre.


Any product that has a copper formulation is generally suggested for treating algae, but in some instances it can become cost prohibitive. Even though EPA approved, our society looks at chemical treatments with a black eye and a microscope. Chemical application is effective if applied correctly, and it is ineffective and negatively viewed when improperly used.  An alternative to using copper is liquid peroxide. This product can be used on a wide variety of algae for commercial and private applications.


Technological advances in microbial research has led to many products that blend beneficial microbes. These blends support the current microbes that are breaking down sludge and nutrients for food. Microbes also require oxygen and should be used with systems that are aerated.


Whether it’s pulling, raking, skimming, or blowing via water species algae, it’s very time and labor intensive. This method can be used when in a crunch for time because an  important wedding or family gather is taking place in a couple of days. Just realize you won’t get it all and you are only applying a band aide. The algae will return.

Water Movement

Everyone has launched off the diving board and found that cool layer under the waters surface. No wonder everyone is always shaking when coming to the surface! We refer to this as stratification. Stratification is the layering of water influenced by ambient temperatures, warmer at the surface, and cooler the further you go down. Temperature different waters also segregate oxygen rich versus oxygen depleted layers. Bottom layers are nutrient rich, low oxygen, and low beneficial bacteria found. Over time, the bacterial decomposition produces hydrogen sulfide gas and methane gas from anaerobic microbes.

Stratification can be de-stratified by moving the water by applying vertical circulation with aeration. Circulation is done with pumps which move water passively.

Aeration can be cost effective way to assist with nutrient reduction and sludge, and increase oxygen in any lake or pond. The goals and costs will depend on which type of aerator is used. Floating aerators work great for providing beauty, de-icing and in shallow waters, but are ineffective for deeper areas.

Diffused aeration systems are great for deeper waters and there are different systems depending on geographical location, electrical availability, goals, and personal preference. Diffused air is sent to diffusers, located on the lake or ponds bottom, via a compressor located near the shore or on a platform on the lake. Diffusers release small bubbles that move the water column up, thus moving the body of water in a circular motion, de-stratifying the lake or pond. This method is preferred for lake or ponds used for recreational swimming because there is no electricity in the water.

Controlling algae is not just one method, but a number of methods, one of which will be best for you. It’s important to first determine goals, costs, time, and available resources. No combination of these methods will work for another pond — remember, there is “no one size fits all.” Be prepared, gather information, find a lake or pond professional, and you are on your way to making the right decision for your unique algae situation. When you are controlling algae, your lake or pond is looking great, everyone will enjoy it, and you will sleep easier at night.